CN111092301A - Graphene broadband wave absorber based on ordered annular slit array - Google Patents
Graphene broadband wave absorber based on ordered annular slit array Download PDFInfo
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- CN111092301A CN111092301A CN201911425898.6A CN201911425898A CN111092301A CN 111092301 A CN111092301 A CN 111092301A CN 201911425898 A CN201911425898 A CN 201911425898A CN 111092301 A CN111092301 A CN 111092301A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/003—Light absorbing elements
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Abstract
The invention discloses a graphene broadband wave absorber based on an ordered annular slit array, belongs to wave absorbing devices in the technical field of terahertz, and utilizes the surface plasma characteristic of graphene. The wave absorbing device is of a three-dimensional periodic structure, and the structure of the wave absorbing device is as follows: the top layer is a graphene annular slit, the middle layer is made of an insulating material, and the bottom layer is an all-metal film and is of a three-layer structure formed by stacking from top to bottom. The invention mainly calculates and simulates the absorption spectrum of the terahertz wave band wave absorber by a finite element method, optimizes the structure of the wave absorber, has the capability of realizing broadband absorption in the terahertz wave band and can effectively tune the absorption intensity. The terahertz wave detector is simple, compact and reasonable in structure and easy to process, and meets application requirements in the fields of terahertz wave communication technology, detection, imaging, photoelectric detectors and the like.
Description
Technical Field
The invention relates to the technical field of terahertz, in particular to a graphene broadband wave absorber based on an ordered annular slit array. The absorber structure can realize broadband absorption, the broadband terahertz wave absorption rate is adjustable, and the absorber structure can be used for terahertz detection, imaging, stealth and other aspects.
Background
Light absorption is a research hotspot in the field of optics, and especially, the research on broadband light absorption attracts more attention because of important application prospects in the aspects of biosensing, military stealth, photoelectric detectors, photothermal conversion and the like. Graphene is a transparent, high-electron-mobility two-dimensional semiconductor material, which can directly or indirectly change its properties such as electron mobility, electrical conductivity, and dielectric constant by means of voltage, chemical doping, and the like. At present, there are two main methods for designing a broadband wave absorber based on graphene metamaterials: one, two or more graphene metamaterials with similar structures and different sizes are combined together to form a super large unit structure. Secondly, stacking multi-layer graphene metamaterials with different geometric dimensions, wherein the multi-layer graphene metamaterials are separated by dielectric layers with proper thicknesses, but the design of the devices faces some problems: the practical application of the structure units is greatly hindered by the problems of overlarge size of the structure units and complicated device preparation process.
The novel metamaterial wave absorber has the advantages of strong broadband absorption, thin thickness, single structure, simple structure, convenience in processing and the like. In addition, due to the Fermi level adjustability of the graphene, the dynamic adjustable performance of the absorption strength can be realized, and the requirements on application in the aspect of terahertz absorption can be met.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a graphene broadband wave absorber based on an ordered annular slit array, which has the characteristics of broadband absorption, thin thickness, single structure, simple structure and convenience in processing.
In order to achieve the purpose, the invention adopts the technical scheme that:
the utility model provides a graphite alkene broadband wave absorber based on orderly cyclic annular slit array which characterized in that: the graphene layer comprises a metal layer, a dielectric layer and an ordered annular slit array.
The beneficial effects of the invention are as follows:
1. the broadband absorber is simple in structure, the broadband absorption effect can be realized only by using a single layer and single graphene, and the absorption rate is not lower than 90% in a specific frequency band range.
2. The wave absorber adopts a periodic structure, has simple and compact structure and is convenient for large-scale integration.
3. The invention utilizes the electrical adjustability of graphene to realize the dynamic adjustable characteristic of broadband absorption rate.
Drawings
FIG. 1: the unit structure of the embodiment of the invention is schematically shown.
FIG. 2: the top graphene layer of the embodiments of the present invention is a top view.
FIG. 3: the absorption curve of the absorber under normal incidence of electromagnetic waves.
FIG. 4: changing the absorption curve when the chemical potential is 0-0.9 eV.
In fig. 1, 1: a metal layer; 2: a dielectric layer; 3: a graphene layer. The metal layer has a length and width p of 35 μm and a thickness t10.2 micron and the thickness of the dielectric layer is t217 microns.
In FIG. 2, the inner radius r of the circular slit of single-layer graphene110.5 microns, outer radius r217 microns.
Detailed Description
The invention is described in further detail below with reference to the figures and examples, but the scope of the invention should not be limited thereby.
The invention designs a terahertz broadband adjustable absorber based on single-ring graphene, and the specific implementation mode comprises the following steps:
fig. 1 is a schematic diagram of a graphene-based broadband absorber. With a period p of 35 microns and a thickness t1The metal layer (1) is used as a reflecting substrate, the middle medium layer (2) is made of silicon dioxide, and the top graphene layer (3) is of a single-layer structure. The metal layer is made of copper material, the thickness of the metal is far larger than the skin depth of the metal in the terahertz wave band, and t is selected10.2 microns for its thickness; the dielectric layer is made of silicon dioxide, and t is selected2Its thickness is 25 microns.
FIG. 2 shows a top graphene pattern with inner and outer radii of a circular slit of graphene r110.5 μm and r217 microns. The invention relates to a reflective absorber in the range of 0.1-4.5 THz.
The chemical potential of the graphene is 0.9eV, and an absorption curve of the terahertz absorber obtained through electromagnetic simulation is shown in FIG. 3.
One of the most important properties of graphene is electrical tunability, and therefore, when the chemical potential of graphene is analyzed to change from 0eV to 0.9eV, the absorption efficiency of a wide frequency band is shown in fig. 4, and it can be seen that dynamic tuning with an absorption rate of 14% to 100% can be achieved between 0eV and 0.9 eV.
Regarding the calculation of the absorption rate, when the incident electromagnetic wave is incident from the free space to the surface of the structure, a part of the incident electromagnetic wave is directly reflected to the free space to form a reflected wave, the rest part of the incident electromagnetic wave is incident to the inside of the structure in the form of a transmitted wave, a part of the incident electromagnetic wave is converted into heat energy or energy in other forms in the form of ohmic loss, and a part of the incident electromagnetic wave continues to propagate forward in the form of a transmitted wave. Therefore, the electromagnetic wave absorption rate expression is: a (ω) ═ 1-R (ω) -T (ω) ═ 1-S11|2-|S21|2(1)
Wherein R (omega) and T (omega) are respectively reflectivity and transmissivity, S11、S21Respectively the reflection coefficient and the transmission coefficient of the absorber.
For a reflective absorber, the function of the 0.2 micron thick metal plate is to block the transmission of electromagnetic waves into the structure, so S210. The electromagnetic wave at this time only needs to calculate the reflectivity and the absorptivity, and the reflectivity is:
R(ω)＝|S11|2(2)
i.e. the absorption rate can be simplified to:
A(ω)＝1-R(ω)＝1-|S11|2。 (3)
the present invention has been illustrated by the above embodiments, but it should be understood that the above embodiments are for illustration and description only and are not intended to limit the invention within the scope of the described embodiments. Furthermore, it will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that many variations and modifications may be made in accordance with the teachings of the present invention, which variations and modifications are within the scope of the present invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A graphene broadband wave absorber based on an ordered annular slit array is characterized by comprising a metal layer, a dielectric layer and a graphene layer of the ordered annular slit array.
2. The ordered circular slit array-based graphene broadband wave absorber according to claim 1, wherein the circular slit structure is circular, elliptical, triangular or polygonal.
3. The ordered annular slit array-based graphene broadband wave absorber according to claim 1, wherein the annular slit structure units are in a square array structure or a hexagonal array structure.
4. The ordered annular slit array-based graphene broadband wave absorber according to claim 1, wherein the period of the annular slit structural unit is 36-46 micrometers.
5. The graphene broadband wave absorber based on the ordered annular slit array according to claim 1, wherein the dielectric constant of the dielectric layer is 2-6.
6. The ordered circular slit array-based graphene broadband wave absorber according to claim 1, wherein the circular slits have a shape of a circular ring, the outer radius of the circular ring is 11 micrometers to 17 micrometers, and the inner radius of the circular ring is 1 micrometer to 15 micrometers.
7. The ordered annular slit array-based graphene broadband wave absorber according to claim 1, wherein the graphene is of a single-layer atomic arrangement structure.
8. The ordered circular slit array based graphene broadband wave absorber according to claim 1, wherein the metal layer is an all-metal thin film.
9. The ordered annular slit array-based graphene broadband wave absorber according to claim 8, wherein the operating frequency of the graphene broadband wave absorber is within a frequency band of 0.1-4.5 THz, and the thickness of the metal thin film is greater than the skin depth of the metal thin film corresponding to the operating frequency band.
10. The ordered circular slit array based graphene broadband wave absorber according to claim 1, wherein the metal thin film is made of gold, copper, silver or aluminum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201911425898.6A CN111092301A (en) | 2019-12-23 | 2019-12-23 | Graphene broadband wave absorber based on ordered annular slit array |
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| CN201911425898.6A CN111092301A (en) | 2019-12-23 | 2019-12-23 | Graphene broadband wave absorber based on ordered annular slit array |
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